1. Field of the Invention
The present invention relates generally to methods and apparatus for splitting wood, and more particularly to a method and apparatus for forcefully moving a trolley to urge a splitting blade into a length of wood, such as a log, with great force by means of rotation of a screw member operably connected to the trolley member by a nut threaded onto the screw member and secured to the trolley member, with the screw member being mounted for rotation in such a manner as to generate tension in the screw member during the splitting operation.
2. Description of the Prior Art
The need for power assisted log splitting equipment has long been realized. One of the more conventional configurations for serving this need involves equipment which urges a wedge through a log held by an abutment. A great number of designs have been proposed defining the means to apply sufficient force to a wedge shaped blade to cause the blade to penetrate the grain of wood, such as logs, to split such wood.
U.S. Pat. Nos. 3,077,214 and 3,242,955 are typical teachings of means by which a splitting wedge blade may be forced into a horizontally positioned log through hydraulic pressure generated by a pump and applied through a piston and cylinder arrangement. Although these designs provide both the power and control necessary to split logs, inclusion of a hydraulic system in the design render the devices somewhat complex and relatively expensive to manufacture in that larger power sources are required because of the inefficiency of hydraulic systems.
Several mechanically actuated, non-hydraulic wood splitting devices have been proposed. U.S. Reissue Pat. No. 13,221, for instance, discloses means by which a pitman arm is driven in reciprocating motion by rotating gears and alternatively providing a splitting and retracting motion through the blade. A similar teaching is found in U.S. Pat. No. 262,591 which discloses an analogous splitting movement but teaches the additional feature of an abutment having variable positioning by means of a screw thread.
A number of teachings utilizing screw threads to urge splitting blades through wood are also to be found. For instance, U.S. Pat. No. 111,333 discloses an arrangement in which a rotatably mounted screw engages an elongated nut which in turn is positioned and located to move a splitting blade as the screw is rotated. The screw, as it rotates to move the nut, is in compression thereby inducing a bending force in the screw and a splitting force acting on the nut. As a result, such screw members must be very sturdy with accompanying energy loses from friction resulting from such oversize dimensions.
U.S. Pat. No. 1,283,195 discloses another arrangement involving a screw member in which the driving nut is fixedly mounted with regard to axial movement. Thus the screw moves out of the nut urging a blade into an adjacent log. Again, the screw is in compression with a bending moment and, as a greater length of the screw member moves out of the nut, the stresses in the screw member increase thereby again mandating a very large, sturdy screw member.
U.S. Pat. No. 1,189,999 is subject to similar criticism as the worm drive urges the screw member into or against a log in a compression mode with substantial length of the screw member being unsupported against bending.
Thus, insofar as the above screw member and nut actuated devices are concerned, the splitting forces are opposed by screw members of brute dimensions to cope with such forces inducing compression and bending of the screw member. This increases the weight and lowers the efficiency of such designs.